The present invention relates to an intervertebral implant for the lumbo-sacral joint.
In the anatomy of the spine, the sacrum, which is situated below the lumbar vertebrae, is constituted by five vertebrae which, during human evolution, have become fused together. The top vertebra of the sacrum, written S1, is jointed to the fifth lumbar vertebra, written L5. This joint thus constitutes the lumbo-sacral joint, or L5-S1 joint, as shown in accompanying FIG. 1.
Each lumbar vertebra presents a middle, posterior projection: the “spinous process”, referred to below as the process 10. The sacral vertebrae have lost their processes over evolution, and instead they retain only respective small residual bosses 12.
In man, certain back pains can be due to stresses associated with relative displacements between two vertebrae acting on the intervertebral disk that is situated between those two vertebrae.